The utility of LANs led to the desire to connect two (or more) networks together. For example, a large corporation might have had separate networks for research and engineering and another for its manufacturing units. These network systems probably used totally different networking technologies and specifications for communicating and were located in different cities, states, or even countries, but it was deemed necessary to “tie” them together. The objective of this and subsequent chapters is to introduce the concepts and issues behind interconnecting LANs. Interconnecting LANs in a campus network or even interconnecting LANs in wide area networks (WANs) incorporate similar concepts and issues. The campus network is a collection of two or more interconnected LANs, either within a building or housed externally in multiple buildings.

5-1 Introduction

Campus Network

A collection of two or more interconnected LANs in a limited geographic area

The framework defining the network layers for linking networks together is defined by the OSI model and was introduced in Chapter 1, “Introduction to Computer Networks,” section 1-3. The OSI model provides a framework for networking that ensures compatibility in the network hardware and software. The concepts behind the hardware technologies used to interconnect LANs are presented in sections 5-2 to 5-5. The properties of a networking bridge are defined in section 5-2. The layer 2 switch is examined in section 5-3, and the router is introduced in section 5-4. An example of interconnecting LANs is provided in section 5-5. The chapter concludes with a section on the concept of auto-negotiation, examining the advantages and disadvantages of this network configuration option.

Table 5-1 lists and identifies, by chapter section, where each of the CompTIA Network+ objectives are presented in this chapter. The chapter sections where each objective is presented are identified. At the end of each chapter section is a review with comments of the Network+ objectives presented in that section. These comments are provided to help reinforce the reader’s understanding of a particular Network+ objective. The chapter review also includes “Test Your Knowledge” questions to aid in the understanding of key concepts before the reader advances to the next section of the chapter. The end of the chapter includes a complete set of question plus sample certification type questions.

TABLE 5-1 Chapter 5 CompTIA Network+ Objectives

Domain/Objective Number

Domain/Objective Description

Section Where Objective Is Covered

1.0

Network Architecture

1.1

Explain the functions and applications of various network devices

5-3, 5-4

1.3

Install and configure the following networking services/applications

5-4

1.4

Explain the characteristics and benefits of various WAN technologies

5-4

1.7

Differentiate between network infrastructure implementations

5-2

1.8

Given a scenario, implement and configure the appropriate addressing schema

5-2, 5-3

1.9

Explain the basics of routing concepts and protocols

5-3, 5-5

2.0

Network Operations

2.6

Given a scenario, configure a switch using proper features

5-4

4.0

Troubleshooting

4.2

Given a scenario, analyze and interpret the output of troubleshooting tools